Relationship Between Brain Volume and Brain Width in Mammals and Birds

Kawabe, Soichiro; Shimokawa, Tetsuya; Miki, Hitoshi; Okamoto, Takashi; Matsuda, Seiji; Itou, Takuya; Kitagawa, Masato; Sakai, Takeo; Hosojima, Misato; Endo, Hideki

doi:10.2517/1342-8144-17.3.282

Cited by 8 publications

(7 citation statements)

References 48 publications

(8 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Only the Ainoshima specimen (KMNH VP 200,009) was subject to this estimation: it lacks the basicranial part, but is not deformed. Brain width and brain volume show a strong correlation (Kawabe et al ., ), and brain volume can be calculated from the following regression formula:

\log y = 2.801 \log x - 0.437,

where y is the brain volume (cm 3 ) and x is the maximum brain width (cm).…”

Section: Methodsmentioning

confidence: 99%

“…In contrast, although this shape is commonly seen in many birds (e.g. Kawabe et al ., , ; Milner & Walsh, ; Smith & Clarke, ), the cerebral hemispheres of Ciconiiformes and Pelecaniformes are round or ellipsoid, and those of Suliformes are more anteroposteriorly elongate (Fig. ).…”

Section: Methodsmentioning

confidence: 99%

“…Brain volume is important information for any discussion of brain morphology, but the damage in plotopterid specimens prevented us from measuring the brain volume directly. Thus the brain volume was estimated using the brain width as a proxy for brain volume (Kawabe et al ., , ). Only the Ainoshima specimen (KMNH VP 200,009) was subject to this estimation: it lacks the basicranial part, but is not deformed.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Enigmatic affinity in the brain morphology between plotopterids and penguins, with a comprehensive comparison among water birds

2013

Self Cite

View full text Add to dashboard Cite

Plotopterids (Aves: Plotopteridae) are extinct flightless birds that were endemic to the North Pacific Ocean. As flightless, wing‐propelled diving birds they exhibit similar skeletal morphology to Sphenisciformes (penguins), especially in their wings. In contrast to the similarity, Plotopteridae have been placed in (traditional) Pelecaniformes in most palaeontological and phylogenetic studies, based on shared characters that are absent in penguins. The postcranial morphology of Plotopteridae has been well studied, but little is known about the cranial morphology, particularly the nervous system. The brain morphology of Plotopteridae, compared with other water birds, could prompt a reconsideration of those previous phylogenetic hypotheses, as the cranial morphology is conservative and could provide powerful signals for the phylogenetic reconstruction. In order to compare the brain morphology of Plotopteridae with that in other water birds (Ciconiiformes, Pelecaniformes, Suliformes, Procellariiformes, and Sphenisciformes), we generated virtual endocasts of Plotopteridae and extant water birds. We investigated the brain morphology of those birds using three‐dimensional geometric morphometric and linear measuring methods. The width of the cerebellum and the length of the floccular lobe varied considerably among water birds, and the relative lengths separate Procellariiformes + Sphenisciformes from Ciconiiformes + Pelecaniformes + Suliformes. The former group had a relatively wider cerebellum and longer floccular lobe, whereas the latter group had a relatively narrower cerebellum and shorter floccular lobe. The relative width of the cerebellum and length of the floccular lobe in Plotopteridae was comparable with that of the former group, in addition to many morphological similarities to the Sphenisciformes brain. On the basis of brain morphology alone, we dare not conclude that Plotopteridae forms a clade with, or belongs to, Sphenisciformes; however, the brain configuration of Plotopteridae is distinctly close to that of penguins, and could possibly reflect their phylogenetic relationship. © 2013 The Linnean Society of London

show abstract

\log y = 2.801 \log x - 0.437,

where y is the brain volume (cm 3 ) and x is the maximum brain width (cm).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Enigmatic affinity in the brain morphology between plotopterids and penguins, with a comprehensive comparison among water birds

2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, multiple regression analysis indicates that (out of length, width and height) maximum brain width contributes most to variation in endocast volume across avian species and has increased relative to brain endocast volume over the course of evolutionary history in birds and mammals (Kawabe et al, 2009). A subsequent analysis of mammalian endocast width and volume indicated a strong linear relationship, although mammalian brains tend to be more slender than avian brains (Kawabe et al, 2013). Neurocranial globularity and endocast length were also identified as a major axis of endocast shape variation across marsupials (Weisbecker et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

The genetic basis of neurocranial size and shape across varied lab mouse populations

et al. 2022

View full text Add to dashboard Cite

Brain and skull tissues interact through molecular signalling and mechanical forces during head development, leading to a strong correlation between the neurocranium and the external brain surface. Therefore, when brain tissue is unavailable, neurocranial endocasts are often used to approximate brain size and shape. Evolutionary changes in brain morphology may have resulted in secondary changes to neurocranial morphology, but the developmental and genetic processes underlying this relationship are not well understood. Using automated phenotyping methods, we quantified the genetic basis of endocast variation across large genetically varied populations of laboratory mice in two ways: (1) to determine the contributions of various genetic factors to neurocranial form and (2) to help clarify whether a neurocranial variation is based on genetic variation that primarily impacts bone development or on genetic variation that primarily impacts brain development, leading to secondary changes in bone morphology. Our results indicate that endocast size is highly heritable and is primarily determined by additive genetic factors. In addition, a non‐additive inbreeding effect led to founder strains with lower neurocranial size, but relatively large brains compared to skull size; suggesting stronger canalization of brain size and/or a general allometric effect. Within an outbred sample of mice, we identified a locus on mouse chromosome 1 that is significantly associated with variation in several positively correlated endocast size measures. Because the protein‐coding genes at this locus have been previously associated with brain development and not with bone development, we propose that genetic variation at this locus leads primarily to variation in brain volume that secondarily leads to changes in neurocranial globularity. We identify a strain‐specific missense mutation within Akt3 that is a strong causal candidate for this genetic effect. Whilst it is not appropriate to generalize our hypothesis for this single locus to all other loci that also contribute to the complex trait of neurocranial skull morphology, our results further reveal the genetic basis of neurocranial variation and highlight the importance of the mechanical influence of brain growth in determining skull morphology.

show abstract

“…The study of fossil endocasts is the only way to understand the nervous and sensory systems of extinct species, but also to constrain inferences drawn from extant taxa only. Several works have demonstrated that the endocast provides a good volumetric approximation of the brain and its major subdivisions in some mammalian groups (e.g., Edinger, 1949; Jerison, 1973; Kawabe et al, 2013), whereas the morphological correspondence between the endocast and endocranial soft tissues is not always direct. Indeed, meninges separate the brain tissue from the bones of the braincase to isolate and protect the former (e.g., Balanoff & Bever, 2017).…”

Section: Introductionmentioning

confidence: 99%

Anatomical correlates and nomenclature of the chiropteran endocranial cast

Maugoust

Orliac

2023

The Anatomical Record

View full text Add to dashboard Cite

Bats constitute a diverse group of mammals highly specialized toward active flight and ultrasound echolocation. These adaptations reflect on their morpho-anatomy and have been tentatively linked to brain morphology and volumetry. Despite their small size and delicateness, bat skulls and natural braincase casts have been preserved in the fossil record and allow for investigating brain evolutionary history and inferring paleobiology. Recent progresses in imaging techniques now allow for virtually extracting internal structures, assuming that the shape of internal cavity casts reflects soft organ morphology. Such a correspondence is not straightforward regarding the braincase cast ("endocast"), because meninges and vascular tissues surround the brain in living organisms and the resulting endocast morphology is a mosaic of the marks left by all these tissues. The hypothesis that the endocast reflects the brain in terms of both external shape and volume has drastic implications when addressing brain evolution, but has been little discussed. To date, a single work addressed the correspondences regarding brain and braincase in bats. Here, taking advantage of the advent of imaging techniques, we review the anatomical, neuroanatomical, and angiological literature and compare the available knowledge of bat's braincase anatomy to a sample of endocranial casts representing most modern bat families. Such comparison allows for proposing a Chiroptera-scale nomenclature for future descriptions and comparisons of bat endocasts. This also encourages further works to formally test what is hypothesized here.

show abstract

Relationship Between Brain Volume and Brain Width in Mammals and Birds

Cited by 8 publications

References 48 publications

Enigmatic affinity in the brain morphology between plotopterids and penguins, with a comprehensive comparison among water birds

Enigmatic affinity in the brain morphology between plotopterids and penguins, with a comprehensive comparison among water birds

The genetic basis of neurocranial size and shape across varied lab mouse populations

Anatomical correlates and nomenclature of the chiropteran endocranial cast

Contact Info

Product

Resources

About